At present, land mines are found in over sixty-five countries in a variety of environmental conditions. A number of different technologies have been employed in demining applications. These include, but are not limited to, rollers, flails, plows, and tillers. Each of these technologies has different performance characteristics, and in most demining applications, combinations of these technologies are used to ensure that the highest possible percentage of mines is detonated. In many situations, rollers are used as a first-pass treatment both to clear mines and also to prepare the soil for subsequent treatments. Compared to other systems, roller-type devices are mechanically simple, easy to maintain, and require less power to operate. Another major advantage is that rollers leave the host environment more intact in comparison to other systems that tend to remove or significantly disturb the soil. However, traditional roller-type devices face a number of drawbacks such as bridging, inconsistent ground pressure, and a lack of customizability.
Most existing roller assemblies make use of stacked or “free-floating” rollers. In this type of design, heavy annular rollers are placed side by side along a single shaft passing horizontally through the central opening of each roller, the diameter of the shaft being significantly smaller than the diameter of the central opening of each roller. This design allows each annular roller to move independently up, down, forward, and backward relative to the shaft to follow terrain variations. However, the maximum range of terrain variation that can be accommodated by such a design is dependent on the diameter of the central opening of the roller. If the variation in terrain along the width of the roller exceeds this dimension, some of the rollers may lift off of the ground, causing incomplete ground coverage and mine clearance (“bridging”). Bridging can also occur when the friction between adjacent rollers prevents a roller from fully contacting the ground. This often happens, for example, when a roller rolls over an obstruction that causes the roller to shift vertically relative to the shaft and adjacent rollers. As the roller comes back down, friction between it and the adjacent rollers prevents the roller from returning fully to the ground surface, leading to incomplete mine clearance. Friction between the rollers and friction between the rollers and the shaft also increases the amount of power that must be provided to operate the system. In addition to these issues, stacked roller-type devices also suffer from a lack of adjustability. Because the force exerted on the ground is dictated primarily by the weight of the rollers, it is virtually impossible to vary the amount of pressure exerted by the system without replacing the rollers. This is particularly disadvantageous since there are currently hundreds of land mine varieties, many of which require different amounts of force to detonate.